| Refactoring |
Example |
|
Add Parameter.
An existing method needs information that was not passed in before. |
 |
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Consolidate Conditional Expression.
Combine sequence of conditional tests into a single conditional
expression and extract it. |
| Before |
After |
CREATE OR REPLACE FUNCTION
GetAccountAverageBalance
( inAccountID
IN NUMBER)
RETURN NUMBER;
AS
averageBalance := 0;
BEGIN
IF inAccountID > 10000 THEN
RETURN 0;
END IF; IF inAccountID = 123456 THEN
RETURN 0;
END IF;
IF inAcountID = 987654 THEN
RETURN 0;
END IF;
-- Code to calculate the average balance
RETURN averageBalance;
END; |
CREATE OR REPLACE FUNCTION
GetAccountAverageBalance
( inAccountID
IN NUMBER)
RETURN NUMBER;
AS
averageBalance := 0;
BEGIN
IF inAccountID < 10000 || inAccountID =
123456 || inAcountID = 987654 THEN
RETURN 0;
END IF; -- Code to calculate the average balance
RETURN averageBalance;
END; |
|
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Decompose Conditional.
Extract methods from the condition. |
| Before |
After |
CREATE OR REPLACE FUNCTION CalculateInterest
( inBalance IN NUMBER )
RETURN NUMBER;
AS
lowBalance NUMBER;
highBalance NUMBER;
lowInterestRate NUMBER;
highInterestRate NUMBER;BEGIN
lowBalance := GetLowBalance();
highBalance := GetHighBalance();
lowInterestRate := GetLowInterestRate();
highInterestRate := GetHighInterestRate();
IF inBalance < lowBalance THEN
RETURN 0;
END IF
IF inBalance >= lowBalance && inBalance <=
highBalance THEN
RETURN inBalance * lowInterestRate;
ELSE
RETURN inBalance * highInterestRate;
END IF;
END; |
CREATE OR REPLACE FUNCTION CalculateInterest
( inBalance IN NUMBER )
RETURN NUMBER;
AS
BEGIN IF BalanceIsInsufficient( inBalance ) THEN
RETURN 0;
END IF
IF IsLowInterestBalance( inBalance ) THEN
RETURN CalculateLowInterest( inBalance );
ELSE
RETURN CalculateHighInterest( inBalance );
END IF;
END; |
|
|
Extract Method.
Turn the code fragment into a method whose name explains the purpose of
the method. |
| Before |
After |
CREATE OR REPLACE FUNCTION
CalculateAccountInterest
( inAccountID
IN NUMBER,
inStart IN DATE,
inEnd IN DATE )
RETURN NUMBER;
AS
medianBalance NUMBER;
startBalance NUMBER;
endBalance NUMBER;
interest := 0;
BEGIN
BEGIN
-- Determine the starting balance
SELECT Balance INTO startBalance
FROM DailyEndBalance
WHERE AccountID = inAccountID &&
PostingDate = inStart;
EXCEPTION WHEN NO_DATA_FOUND THEN
startBalance := 0; -- Determine the ending balance
SELECT Balance INTO endBalance
FROM DailyEndBalance
WHERE AccountID = inAccountID &&
PostingDate = inEnd;
EXCEPTION WHEN NO_DATA_FOUND THEN
endBalance := 0;
END;
medianBalance := ( startBalance +
endBalance ) / 2;
IF medianBalance < 0 THEN
medianBalance := 0;
END IF;
IF
medianBalance >= 500 THEN
interest := medianBalance * 0.01;
END IF;
RETURN interest;
END; |
CREATE OR REPLACE FUNCTION
CalculateAccountInterest
( inAccountID IN NUMBER,
inStart IN DATE,
inEnd IN DATE )
RETURN NUMBER;
AS
medianBalance NUMBER;
startBalance NUMBER;
endBalance NUMBER;
BEGIN
startBalance := GetDailyEndBalance (
inAccountID, inStart );
endBalance:= GetDailyEndBalance (
inAccountID, inEnd );
medianBalance := CalculateMedianBalance (
startBalance, endBalance );
RETURN CalculateInterest ( medianBalance );
END; |
|
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Introduce Variable.
Put the result of the expression, or parts of the expression, in a
temporary variable with a name that explains the purpose. |
| Before |
After |
CREATE OR REPLACE FUNCTION
DetermineAccountStatus
( inAccountID
IN NUMBER,
inStart IN DATE,
inEnd IN DATE )
RETURN VARCHAR;
AS
lastAccessedDate DATE;
BEGIN -- Some code to calculate lastAccessDate
IF ( inDate < lastAccessDate && outdate >
lastAccessDate )
&& ( inAccountID > 10000 )
&& ( inAccountID != 123456 && inAcountID
!= 987654) THEN
-- do something
END IF;
-- do another thing
END; |
CREATE OR REPLACE FUNCTION
DetermineAccountStatus
( inAccountID
IN NUMBER,
inStart IN DATE,
inEnd IN DATE )
RETURN VARCHAR;
AS
lastAccessedDate DATE;
isBetweenDates BOOLEAN;
isValidAccountID BOOLEAN;
isNotTestAccount BOOLEAN
BEGIN
-- Some code to calculate lastAccessDate
isBetweenDates := inDate < lastAccessDate &&
outdate > lastAccessDate;
isValidAccountID := inAccountID > 100000;
isNotTestAccount := inAccountID != 123456 &&
inAcountID != 987654;
IF isBetweenDates && isValidAccountID &&
isNotTestAccount THEN
-- do something
END IF;
-- do another thing
END; |
|
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Parameterize Methods.
Create one method that uses a parameter for the different values. |
 |
|
Remove Control Flag.
Use remove or break instead of a variable acting as a control flag. |
| Before |
After |
DECLARE
controlFlag
:= 0;
anotherVariable := 0;
BEGIN
WHILE controlFlag = 0 LOOP
-- Do something
IF anotherVariable > 20 THEN
controlFlag = 1;
ELSE
-- Do something else
END IF;
END LOOP;
END; |
DECLARE
anotherVariable := 0;
BEGIN
WHILE anotherVariable <= 20 LOOP
-- Do something
-- Do something else
END LOOP;
END; |
|
|
Remove Middleman.
Get the caller to call the method directly. |
| Before |
After |
CREATE OR REPLACE PROCEDURE AProcedure
parameter1 IN NUMBER;
"¦
parameterN IN VARCHAR;
AS
BEGIN
EXECUTE AnotherProcedure ( parameter1, "¦,
parameterN );
END; |
|
|
|
Remove Parameter.
Remove a parameter no longer used by the method body. |
 |
|
Rename Method.
Rename an existing method with a name that explains the purpose. |
 |
|
Reorder Parameters.
Change the order of the parameters of a method. |
 |
|
Replace Literal With Table Lookup.
Replace Code constants with values from database tables. |
| Before |
After |
CREATE OR REPLACE FUNCTION CalculateInterest
( inBalance IN NUMBER )
RETURN NUMBER;
AS
interest := 0;
BEGIN
IF inBalance >= 500 THEN
interest := medianBalance * 0.01;
END IF;
RETURN interest;
END; |
CREATE OR REPLACE FUNCTION CalculateInterest
( inBalance IN NUMBER )
RETURN NUMBER;
AS
interest := 0;
minimumBalance NUMBER;
interestRate NUMBER;
BEGIN
minimumBalance := GetMinimumBalance();
interestRate := GetInterestRate();
IF inBalance >= minimumBalance THEN
interest := medianBalance * interestRate;
END IF;
RETURN interest;
END; |
|
|
Replace Nested Expression With Guard Clauses.
Remove nested if conditions with a series of separate IF statements. |
| Before |
After |
BEGIN
IF condition1
THEN
-- do something 1
ELSE
IF condition2 THEN
-- do something 2
ELSE
IF condition3 THEN
-- do something 3
END IF;
END IF;
END IF;
END; |
BEGIN
IF condition1
THEN
-- do something 1
RETURN;
END IF; IF condition2 THEN
-- do something 2
RETURN;
END IF;
IF condition3 THEN
-- do something 3
RETURN;
END IF;
END; |
|
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Replace Parameter With
Specific Methods.
Create a separate method for each value of the parameter. |
 |
|
Split Temporary Variable.
Make a separate temporary variable for each assignment. |
| Before |
After |
DECLARE
aTemporaryVariable := 0;
farenheitTemperature := 0;
lengthInInches := 0;
BEGIN
-- retrieve farenheitTemperature
aTemporaryVariable := (farenheitTemperature
- 32 ) * 5 / 9;
-- do something
-- retrieve lengthInInches
aTemporaryVariable := lengthInInches * 2.54;
-- do something
END; |
DECLARE
celciusTemperature := 0;
farenheitTemperature := 0;
lengthInCentimeters := 0;
lengthInInches := 0;
BEGIN
-- retrieve farenheitTemperature
celciusTemperature := (farenheitTemperature
- 32 ) * 5 / 9;
-- do something
-- retrieve lengthInInches
lengthInCentimeters := lengthInInches *
2.54;
-- do something
END; |
|
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Substitute Algorithm.
Replace the body of the method with the new algorithm. |
|
